


C is for Cthulhu

by samvelg



Series: A Study in Lovecraftian!Harry Potter [1]
Category: A Study in Emerald - Neil Gaiman, Cthulhu Mythos - Fandom, Cthulhu Mythos - H. P. Lovecraft, Harry Potter - J. K. Rowling
Genre: A Study in Emerald, Alternate Universe - Everyone is an eldritch horror, And yawning existential terror, Body Horror, Crossover, Cthulhu Mythos, Eat The Rude, Eldritch, Eldritch Horrors, Gen, Lovecraftian, Lovecraftian Monster(s), Monster puberty ftw, Oh man the dumb jokes I want to make, Ph'nglui mglw'nafh Harry Potter Privet Drive wgah'nagl fhtagn, Pureblood Culture (Harry Potter), Pureblood Culture now with added tentacles, Summon an eldritch abomination start the year off right, ia ia Harry Potter, magic is known
Language: English
Status: In-Progress
Published: 2019-01-04
Updated: 2019-02-11
Packaged: 2019-10-04 03:37:50
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 3,932
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/17297015
Author URL: https://archiveofourown.org/users/samvelg/pseuds/samvelg
Summary: For as long as he can remember he's been waiting. It doesn't matter if it's for his next meal or the day he can finally leave, it feels as though his entire life can be defined as the state of anticipation for something, anything to take him away from here to the magical world he was born into.Or, how whiling away the months and years at Privet Drive is better and worse when he knows from the beginning that he's not supposed to be here.





	1. The Old Ones were...

**Author's Note:**

  * Inspired by [Prophet of the Grace of Ba'al](https://archiveofourown.org/works/1213741) by [Chi-chi-chimaera (gestalt1)](https://archiveofourown.org/users/gestalt1/pseuds/Chi-chi-chimaera), [gestalt1](https://archiveofourown.org/users/gestalt1/pseuds/gestalt1). 



> Ok, so this latest insane literary experiment will be a series of shorts and oneshots about what if Harry and all the other magical folks were descended from eldritch monstrosities whose very existence makes reality bleed around the edges. I've loved eldritch aus for ages and recently read an epic one which was a masterful crossover between A Study in Emerald (Neil Gaiman's awesome Sherlock Holmes/Lovecraft crossover fanfic) and Hannibal, and it was so glorious it made me lose my goddamned mind even faster than gazing into the depths of the eternal abyss. 
> 
> And then me being me, I sat there for the better part of a week trying to work out how the hell to achieve something similar in the HP universe. If you want to get a primer before starting then here is Neil Gaiman's excellent short story A Study in Emerald:  
> http://www.neilgaiman.com/mediafiles/exclusive/shortstories/emerald.pdf  
> If you can't be assed then just keep in mind that nearly a thousand years ago the Great Old Ones came to Earth to save humanity from themselves (and the Void, can't forget about that). After what I imagine to be the quickest conquest in human history they now reign over all the kingdoms of the world as mostly benevolent, be-tentacled Royalty with glowing green blood, and only now and then eating people or inflict them with ecstatic madness. 
> 
> Where the crossover happens is that all magical folks are Nobility, which is to say descendants of humans and the Royal Gods, so magic isn't secret so much as it is very very exclusive. Baby Nobles moult around age 10-11 and present, meaning they physically grow into their monster heritage a little and gain access to their magic, after which they can attend Hogwarts. There's a ton of worldbuilding going into this but in the interest of showing not telling you'll experience it mostly as Harry does, though if you're confused feel free to ask questions in the comments.

The boy lives in a quiet corner of the Kingdom of New Albion, which under the just and merciful reign of Her Majesty Queen Victoria Gloriana has seen relative peace for nearly a thousand years. 

His parents were Nobility but they're long dead, and despite them clearly hating him he somehow ended up with his mother's sister, her husband, and their son. His relatives never hurt him, not really, but he is unwelcome here and behind closed doors they make their displeasure known in sharp actions and sharper words.

Maybe it's a symptom of his discontent but his skin never feels like it fits, it always stretches too tightly over bones and tendons which while undeniably parts of him weren't quite the all of him. His aunt likes telling him he's proof that his parents were so weak they were killed by Restorationists when he was only one year old, though if that's the case he's unsure how he somehow survived as a baby with nothing more to show for it than a lightning bolt shaped scar on his forehead when two adult Nobles didn't.

Whatever the reason every day spent here is a day he has to press down, has to hide. A day that he can't forget to make sure the fleshier parts of himself don't show the whole truth of himself. It's frustrating of course. He is a born predator after all and weakness, faked or otherwise, doesn't feel natural to him.

But as small as he is, stuck with unfriendly caretakers and his first moult on the horizon but still not here, he knows that in the absence of strength he has to be smart instead. That however much he hates it, it's far better to pretend a docility which is as protective as it is untrue. After all, none of the more dangerous members of the Blood Royal could possibly feel threatened by the orphaned runt of a mudblood he comes across as, or feel compelled to remove a potential future competitor while he is still small and with no Kin to defend him.

Starving a Noble is monumentally stupid, even an immature one, but the Dursleys have made quite the artform of it over the years. They've long worked out just how much they can push him into dead-eyed, gnawing hunger and just how much to feed him afterwards to keep him going without straight up going feral on them. It makes sense practically speaking, after all, he might be of their blood but only through a technicality. Never one of their own though, an obligation they accepted for a reason they've never actually explained to him but never accepted as part of their family.

With that in mind, them keeping the bulk of their resources for themselves and their own child is sensible enough, he wouldn't even really hate them for it if they weren't also apparently determined to see him dead of neglect before he can even present and get the hell out of here. There were after all plenty of other reasons for him to hate them.

Just one more year to go.

The mantra is so familiar he suspects if he got curious enough to open himself up he'd find variations of it it carved on the inside of his ribs. Just one more year until his first moult when he'll present as a Noble and gain access to his magic, and then he'll be going to Hogwarts School of Occultism and Cthonics.

While shrouded in secrecy he knows as much as most do, that it's a boarding school somewhere north in the wilds as well as the only school for Nobility in all of New Albion. He knows his aunt and uncle are hoping Dudley will present and earn his place there too, the prestige of having a Noble child even if they aren't Nobility themselves enough to give them the standing in society they so desperately crave. He also knows it's never going to happen, not in a million years.

They might be determined to delude themselves but it's no mystery to him what a baby Noble smells like, he knows the scent of second-hand Royalty from his own skin and the rare others he's passed in the street in this far-flung, quiet corner of suburbia. No matter how badly they hope it's far more likely that the long dead Roman God will resurrect into the world than Dudley Dursley presenting as Nobility. Even though they should know better than to fight against fate they still feed their oversized offspring constantly, as if an excess of nutrition could possibly overcompensate for all the fundamental ways in which he is lacking. Not even the small cuts of slick red meat which Vernon brings home late at night wrapped in nondescript brown paper will change that.

On the very rare occasion this happens it doesn't matter that he's fairly certain that he _really_ doesn't want to know where it comes from, it's still a travesty that it's wasted on Dudley when he can't even eat it raw like something in his hindbrain insists it should be. Locked in his room the scent of it grilling floats up through the air vents, makes his mouth water and abdomen clench until he's grinding his blunt, useless milkteeth to stop himself from gnawing on his own flesh until green ichor drips and stains the carpet. Not again.

That's one of the most forbidden things at Privet Drive actually, bleeding. Because when he bleeds they can't pretend he's inferior to them anymore, the muddy red-brown of their own blood barely tinted green enough to count for much of anything next to the rich forest colour of his own. While not the holy, phosphorescent emerald of true Royalty it isn't too far off either, the only gift of his dead father he has apart from the name he isn't currently allowed to claim. Not yet. P'ttrrr is a Noble name after all even if he's the last one to carry it, one which no-one who is passingly familiar with the Noble Houses of New Albion wouldn't recognise for what it was. So between the Dursley's bitterness and his own paranoia he goes by Harry Potter for now.

The human name grates on him as much as his human skin does, never fitting right. As small and useless as he feels he often wonders what he'll look like once he's moulted. So many long, hungry nights pass with him anticipating the relief of when his form-self will start to match his mind-self better, trying to imagine the more forgiving shape his skin will take until his second moult at seventeen when he'll reach full maturity and finally be what he knows he's meant to be. There are no pictures of his parents in the house, either their Noble forms or their more human ones. But sometimes when he dreams the comforting shadows have antlers and more eyes than he can count, and he likes to pretend that it's them.

According to a book he found in the public library the Progenitor of the P'ttrrr lineage was Northot, The Thing That Should Not Be, who despite being the offspring of the Outer God Shub-Niggurath, the Emperor of all China, spent a lot of time in the court of Her Majesty in the early years after humanity's Deliverance before venturing out to wander the cosmos. As far as his mother's side goes, if the Dursley's bragging is anything to go by they are apparently of the bloodline of Cyäegha, The Destroying Eye. Descendants of Her lineage are especially rare these days, Noble or otherwise, Her nihilistic temperament meaning She never bothered creating many offspring after the initial novelty wore off. It doesn't help that Her Blood is more fickle than most and usually all-or-nothing in its gifts, ending in mudbloods more often than not even back when there weren't centuries of separation from the source.

If Petunia's bitter rants are true then Lily had the vivid green eyes of Cyäegha from birth, the crystalline emerald green which so enchanted any of the Blood Royal. Thanks to them he likes to imagine it came as no surprise when she presented as a Noble and manifested magic of her own, no surprise when she attracted the attention of someone like the young Duke Jamessth P'ttrrr. And as he's inherited his mother's green eyes just as much as he has his father's green blood he knows down to his mortal bones and the not-so mortal spaces in between them that when his own time comes he will be strong too.

Sometimes in the dead of night when he is locked in his room (it used to be the cupboard under the stairs until two years ago, when a Noble Vernon works with came over for dinner and was curious as to why he could smell another Noble inside it) he waits until they're sleeping and allows his control to slip. Allows the fixed, unmoving light of the Gods stars to shine down on his bare shoulders and back where he's dotted with clusters of delicate scales, flexing his too-few limbs and ruffling the soft, downy black feathers hidden in his wild black hair as he whispers his true name.

It's unclear how he knows it, too young to remember anything of his life before the attack which orphaned him but the impression of safe warmth and an eerie flash of green light. Maybe it's instinct or maybe it's imprinting, because he still hears it echoing in the depths of his mind every time he stares up at the comforting radiance of the crimson moon.

Harrreyhlu Jamessth P'ttrrr.


	2. The Old Ones are...

**Summary for the Chapter:**

> Ever since the solstice the moon has seemed like it was laughing at him, like the stars were just waiting for the punchline to some unheard joke. 
> 
> In hindsight this was probably a sign of things to come which he should have paid a lot more attention too.

**Notes for the Chapter:**

> Still finishing up the next chapter of The Historical Importance because I'm moving house and it's time-consuming and stressful, but this chapter was already mostly done and a very enthusiastic anon on tumblr got me feeling the eldritch!harry potter vibes again so I spent my evening off getting it finished. So yeah, cheers for the encouragement anon I hope you dig it ♡
> 
> CW - Harrry hunts and eats miscellaneous animals.

Harrry is a few weeks shy of his eleventh birthday when his first moult begins, and the _bitingfreezingburning_ comes on fast just like everyone warns it will.

Ever since the solstice the moon has seemed like it was laughing at him, like the stars were just waiting for the punchline to some unheard joke. In hindsight this was probably a sign of things to come which he should have paid a lot more attention too.

As well as enduring the judgment of nosy celestial bodies he's been feeling jittery for days, the press of mortal skin tighter than ever and his nerves frayed almost to breaking just like the nearly worn-through knees in his second-hand jeans.

Not sure where the jeans are now.

Odds are good they were one of the first casualties once the door closed and he could finally _finally_ **_finally_** let go and give in to everything he was always meant to be. Granted he's less sure why letting go explains what he's fairly certain are hooves but hey, no one ever said that monster puberty was going to be easy and Harrry's never been a quitter.

He just hopes someone managed to save his glasses.

More times than he can count he's imagined this, reading whatever books he could get hold of and diligently watching the tapes they play in health class and wondering what it was going to be like. It quickly becomes apparent however that he might as well have been trying to comprehend the Void. The glorious agony of the moult is an icy inferno which makes him shudder and shake and scream with perhaps more throats than he rightfully owns just yet, but by now it's only a matter of time so who's counting.

All things considered he's lucky that he was in class when he eventually snapped under the weight of his own becoming, even though a few of the human children were knocked unconscious with nosebleeds as reality began to warp dangerously around the weird, screaming skinny kid in the back row. Despite this being a school predominantly attended by humans and mudbloods there is still a couple of the Crown-mandated caves set aside underneath the lowest basement level for just such an event. While not the rumoured crystal lakes hidden deep under London used by high ranking Nobility it's still a comforting womb of dark earth and stone, with enough space for him to moult in safety and enough warding to contain the overflow of his nascent magic.

The Godling heirs of the Great Old Ones, the trueborn Royals of the Blood with no taint of mortality in Their holy emerald veins, They need the crushing black depths of the open ocean when They moult. While it's not the rich, primordial ichor of the Cerenerian Sea it's still the closest you can get to it on this planet, on this plane. For those like Harrry though, Nobility who are of the New World as well as the Old, no one is quite sure why but they need to be cradled in the earth in order to truly come into their own.

Not even the time he slipped and broke his collarbone and his leg trying to clean out the gutters holds a candle to just how much this hurts. It's the kind of pain which no full human could ever possibly understand with their inability to comprehend an existance spent simultaneously on multiple levels of reality. Some Nobles go mad from it, those too strong or too human to be able to withstand the inhuman rigours of the moult.

During his more lucid moments (in between feeling his cells remake themselves from the atoms up and listening to his bones snap so that forever can pour inside) Harrry wonders what might have happened if he hadn't been so fortunate in his timing. If he'd been at Privet Drive when his moult began in earnest the Dursleys definitely wouldn't have taken him to the one of the publicly accessible moulting caves like they were supposed to. No, far more likely to be locked into his room if he was lucky and his old cupboard under the stairs if he wasn't. With Vernon's temper it's entirely possible that he'd have been killed outright while he was still weak, all for the unforgivable crime of daring to be destined for greater things than they could ever be.

Pointless to dwell on the untaken paths. Here he's cradled deep in the earth and safe from his relatives and any feral Nobility who might smell him, because while blood or the Blood they might be Kin they are not. Other young Nobles might not have to worry so much about such things but Harrry has never had that luxury. Growing up as isolated as he has he knows the truth, that no matter what everyone likes to think Blood is not everything.

While he understands and appreciates where he stands on the food chain, nowhere near the top but a lot further up than most, this isn't because he thinks of his self as inherently superior to those below him. On the contrary, it's simply that he doesn't care in the slightest if a person is a human or a Noble or the Void-damned Queen of New Albion Herself, all that matters to Harrry is how a person treats him. By that metric alone there are precious few he would allow to walk at his unprotected back on a good day let alone trust with his safety while he is vulnerable, and the Dursley's are light years away from being anywhere near that list. There's so many good reasons to hate them after all.

So, while Harrry has never to date been tempted to eat anything which he could conceivably hold a conversation with, deep in the throes of his moult as he is the absurdly pleasing idea of hunting the Dursley's down through the night-time streets of Little Whinging is making his mouth water.

Well, mouths. Not sure how many there are exactly, but he's reasonably confident he'll work it out at some point.

Stars, but he is just so _hungry_.

It's impossible to imagine he's ever known what hunger was before now, despite a childhood perpetually defined by it. Maybe it's that while being hungry isn't in itself new Harrry has never actually wanted to feel a life ending under his teeth before, to the point where he's not sure if right now he could stop himself from savaging anything with a pulse which came within striking range of his various limbs.

Mercifully, at some point a chute near the door opens and he's lunging before even knowing why. Half of it's devoured by his new mouths (still not sure how many, beginning to suspect it changes) before registering that it's some kind of dead animal. Sadly it's not warm, not fresh enough for him to properly taste the life in it. A little disappointing but the blood still drips ever so nicely, the bones not too thick for his young jaws to snap to reach the marrow, and it's close enough as never mind.

It quickly becomes apparent that having something in his stomach is giving the vicious energy remaking him a second wind, because the world is unfolding like a flower made of screaming galaxies and it has rather a lot more corners than it used to. The pleasure of the raw, chaotic energy pulsing through him in shuddering waves is terrible, it's tectonic; he never wants it to end.

Almost as pleasing is how when the door opens again in a few days it will be by a Crown Magister here to officially register him as Nobility and confirm his placement at Hogwarts. There will be no way for the Dursleys to lie and cover up his heritage anymore, no way for them to touch him. Young Nobles in general but especially those of his rank have the inalienable right of superiority over humans and even mudbloods, to the point where he could probably kill them in the street and not face much in the way of censure for it even if he didn't file the appropriate applications for hunting rights in advance.

All members of the Blood Royal are predators no matter how purely their heritage breeds true. And while humans still easily outnumber them by an order of magnitude, between their strength and longevity it wouldn't be hard for a particularly determined one to thin the human population considerably if left unchecked. But thanks to the wisdom of Her Majesty and the strict hierarchy so deeply, instinctively ingrained in Royalty and Nobility alike the laws around who is allowed to hunt what and when are equally strict.

Despite all of this however it's understood that the young don't always have control over their more violent instincts right after they first present, especially if they are provoked or attacked. While the more liberally-minded Nobles like to get up in arms about human rights, the fact remains that as long as you can make a solid argument for just cause and you don't attack anyone of significance it's usually just treated as a youthful indiscretion and indulgently overlooked.

Lost in fantasies of the hunt Harrry imagines testing the speed of his new limbs and the sharpness of his new teeth on his relatives, daydreams about gulping the smell of fear-sweat deep into his lungs while red moonlight glints off the slick wet pools of their blood. Some part of him knows instinctively that he was born to run, knows that once he is fully grown he'll be so fast there will be precious few who will ever be able catch him or escape from him. Between his pedigree and his wicked new body parts if he actually wanted to see them dead by his own hands he could do it, and even if he never acts on it the knowledge he still could is wonderful.

Harrry is pacing his cave and dreaming of running down his cousin like a particularly fat rabbit when an especially earth-shattering spasm hits him like a bus and makes him see stars. It hurts so much it takes him a few seconds to realise that yes, that isn't just a metaphor and he is actually seeing actual stars despite being very much underground.

In between the impossible vision of spacetime burning the world is fracturing into fire and colour all around him, and even his spine is doing something he wasn't entirely aware spines could do. Harrry is somewhat impressed, would no doubt be more so if he wasn't already far too busy screaming that he's even being distracted from imagining what Dudley's pancreas tastes like.

It seems overwhelming and it is, but after a while even bearing witness to the untold horrors of cosmic cataclysm gets old. Gnawing on leftover bones helps with the teething pains, distracts him from hunger not fully satisfied.

Sometimes he scratches at the door, whining pitifully in the back of his throats. Maybe someone hears him or maybe his voracious appetite was anticipated, because eventually another dead animal tumbles down the chute and onto the broad, flat stone positioned underneath it.

This one is bigger, fresher, and it's still all for him. Harry laughs, ecstatic, as he gluts himself on it. There is blood staining his hands all the way up to his elbows and drying his hair and feathers together in clumps. If this is his first taste of life as Nobility then he can already tell he's going to like it very much.

More time, more pacing, more multi-dimensional growing pains and more visions of exquisite devastation. Hours pass like this, or maybe it's days. There's no sun underground to mark the passage of time and his government-funded school can't afford what it would cost to get something as fickle as electronics to work somewhere purpose-built for magical eruptions.

In here it's just him and the earth and some softly glowing crystals at the door end of the cave to break the gloom, though the opposite end of the cave is still reassuringly dark and has some nice big rocks to hide behind whenever the light gets to be too much which is often. With how many more directions he can see in now he thinks he has a lot more eyes than he used to, which would explain some of that oversensitivity.

Somewhere between Harrry contemplating what his classes will be like at Hogwarts and screaming himself hoarse the chute opens again, but to his shocked delight this time the animal is _alive_. He thinks it might be a goat of some kind, because it has four legs and stars is it fast.

It runs and runs in circles and tries valiently to escape him, but the cave is only so big and there's no way out except for the warded and triple bolted door which even Harrry can't open from the inside.

He plays with it, slowing down and letting it get ahead before chasing it down again and again. A memory of Petunia telling Dudley not to play with his food briefly surfaces, but he's far too busy indulging his predatory instincts to care.

Part of him wants to kill it immediately of course, the throbbing energy in his bones and his blood which just has prey-prey-prey-bite-kill-eat-prey playing on repeat. But it's the first living thing he's seen in what feels like forever, and if life with the Dursleys has taught him anything it's that you should always savour the good things when they come.

Eventually though he corners it between the rocks, exhausted with trembling legs and nowhere else to run. Harrry opens up all of his mouths, his heart full to bursting and made of nothing but sharp teeth and power and joy, and then he strikes.

**Notes for the Chapter:**

> Come scream into the void with me!  
> http://samvelg-likes-things.tumblr.com

**Author's Note:**

> If you love Lovecraftian bullshit as much I do then yay, I hope you liked it! If you only clicked on this fic to fill the time until Historial Importance is saved from review team purgatory then congrats if you made it this far! I still consider Harry's horcrux misadventures to be my main fic, but since I can't post new chapters for now I figured I might as well share this wonderful crossover disaster in the downtime.
> 
> Whether you want updates on my progress getting Historical Importance up again for your viewing pleasure or just want to scream into the void with me come find me on tumblr! http://samvelg-likes-things.tumblr.com/


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